Platinum Metals Rev., 1962, 6, (2), 56
Cobalt-Platinum Magnets Resist Corrosion
The combination of outstanding magnetic properties and resistance to chemical attack has made possible the use of Platinax II cobalt-platinum alloy magnets in conditions where ferrous magnets would suffer severe corrosion. The photograph shows an apparatus developed by Thorn-A.E.I. Radio Valves – Tubes Ltd for the electrolytic polishing of nickel radio valve components. In this equipment are eight Platinax II magnets, each 0.375 inch in diameter by 0.2 inch long, attached to the positive electrode. The nickel components, which have to be highly polished both internally and externally with no contact marks beyond the closed end, are held in position by these magnets. With a high current density in a strongly acidic electrolyte operating at 60 to 70°C there have been no apparent burns or marks at the point of contact between the nickel parts and the magnets, which have been in use for over a year without showing any sign of attack or of loss in magnetic strength.